Control of arcing electrodes



Jan. 15 1924. 1,480,908

E. H. HORSTKOTTE CONTROL OF ARCING ELECTRODES Filed Oct. 14. 1921Inventor: Edward H. Horstkotte,

H is Apto ne g.

UNITESD STATES JP nnwm a. nonsrxdr'm, or oscnmmcramr, new roux,ASSIGNOB'TO enmmu.

' mmc'rmc couramz, A conromrrrpn pr new roux.

P atented 15, 1924.

" lpplication filed Octobeffll, 1921. Serial No. 507,706. 1

To all whom it may concern." Be it known that I, EDWARD H. Honsr- KOTTE,a citizen of the United States, residing at Schenectady, in the countyof Schenectady, State of New York, have invented certain new and usefulImprovements in Control of Arcing Electrodes, of which the following isa specification.

' My invention relates to an improved control for arcing electrodes.Although the invention is particularly useful in the control of thearcing electrodes of an electric furnace, the invention is notnecessarily limited to the control, of fur nace electrodes, but may alsobe used in the control of other electric translating devices as well.

In prior electrode controlt arrangements, electromagnetic switchmechanism has been provided for controlling the arcing relation' of theelectrodes and the switch mechanism has been automatically operated toeffect the control" of the electrodes in response to a condition of thearcs supported Due to the self-inducby the electrodes.

, tion of switch electromagnets and the metromagnetic switch mechanism,and the in-- chanical inertiaof the movable elements of the switches,the control of the electrodes has been tardy and thereis also a tendencyto cause' overrunning. Electroresponsive means such as electric motorshave heretofore been provided for regulating the electrodes under thecontrol of the said elecertiaand selfinduction of the motors has beenadded, to thestardyeffect and the tendency to overrunning.

One of the objects of the invention'is to eliminate the electromagneticswitch mechanism heretofore provided. in arrangements for controllingelectrodes and other translating dev1ces,.and to minimize the 'tardyeffect and the tendency to overrun ning, so that. the electrode or othertranslating device will be governed practically simultaneously with theoccurrence of the electrical condition or conditions which makedesirable the control of the electrode or other translating device.

In carrying my invention into effect as applied to the control of thearcing electrodes of an electric furnace, I provide an electric valvefor controlling the arcing relation of the electrode. The electric valvemay be of an electron discharge type, such 1,4sb,9os Free.

Arm-rot CQNTBOL OF ABCING valve is practically simultaneous with theoccurrence of the electrical condition which makes necessary aregulatien of the electrode. In the embodiment of my invention which Ihave selected for purposes of illustration, the electric valve controlsthe energization of an electrode motor by.controll1ng.the energizationof a generator 'supplyin current to the motor, and although t earrangement which I have thus selected has certain'important advantages,

invention can be carried out by other means. 7

F or a better understanding of the invention, reference is. had to theaccom anying drawing in which T have shown or pur- V poses ofillustration the particular embodi- "I conceive that the broad featuresof the ment'of the invention above referred to.

support arcs for heating the bath contained in the furnace.

The separately excited di-' redt current motors 14, 15 and 16 are pro-"vided as the electroresponsive means for controlling the arcingrelation'of the electrodes 10, 11 and 12 respectively. The energizationof these electrode motors is controlled by means comprising the electricvalves 17,-18 and 19 respectively. Theelectric valves shewn are of theelectron discharge type, in which a hot cathode 2O cooperates with theplate or anode 21 within a container 22. A hot cathode electrondischarge device such as a kenetron is satis factory for the purposes ofmy invention. The electric valvesare connected so as to be responsiveto..the electrical condition of e the are supported by the electrodecontrolled by the valve. Thus, the valve maybe responsive'to the flow ofcurrent in the circuit of the electrode controlledthereby, and forcontrolling the electrode in response to this electrical condition, Ihave provided current transformers 23, 24 and 25 for the valves former.1 Thus, for example, the hot cathode is connected across a portion "ofthe secondary windings of the current transformer 23 and a resistor 26is included in the hot cathode circuit so as to regulate the heatingeffect and thereby the current in the plate circuit. By means of theresistors in- Y cluded, in the hot cathode circuits of the electricvalves, the operation of each electrode motor may be adjusted withrespect to the other electrode motors, so that after having, beenadjusted, the electrode motors will be caused to cooperate to regulatetheir respective electrodes in the manner desired.

Instead of employing the plate current of a valve or rectifier todirectly control its respective electrode motor, I prefer to control theelectrode motors by controlling the energization of separately exciteddirect current generators 27, 28 and 29, each having its armaturedirectly connected to supply the currentfor the armature, of itsrespective electrode motor. ,These generators may all be mounted on bneshaft and be driven by an alternating-current motorv 30 energized fromthe source of supply 31 through the transformer 32, to which the furnaceelectrodes are also connected' Each of these generators is provided witha field winding supplied with current from an exciter 33mounted on theshaft of the alternating current driving motor 30 so as to be driventherefrom. The -exciter also supplies the current for theseparately-excited fields of the electrode motors. The generator 27 isprovided with a shunt field 34 which" is energized by the platecurrentof the rectifier 17, and this'shunt field 34 is'diiferentially woundwith respect to the shunt. field 35 of the generator. The generators 28and 29 "are provided with simila r fields and are controlled in asimilar manner. The arrangement is such that when the current in thecircuit of the electrode 10 is substantially normal, the two fields34and 35 substantially neutralize each other so that the voltage suppliedto the armature of "the electrode motor 14 is practically zero value,but in case the current should either increase 7 or decrease from thepredetermined normal,

the value of the voltage and the direction of the current supplied tothe armature of the electrode motor-'14; will be such that the motorwill be caused-to practically simultaneously operate the electrode 10 tosuch a position that the condition in the arc circuit of the electrodeis automatically and quickly brought back to normal.

As thus constructed and arranged, the operation of my invention is asfollows: Assume that the equipment is operatin and that the resistors inthe cathode circults of the rectifiers have been properly adjusted, thevalue of current supplied to the separately excited fields of thegenerators and .the value of current supplied to the sepa- 'ratelyexcited fields of the motors from the exciter 23 have been adjusted sothat a normal; condition of the arcing relation of the electrodes hasbeen established, and that it is desired that this normal relation bemaintained. Assume that the current in-th'e circuit of the electrode 10increases above 1 ,the generator 27 will also be increased.

This will destroy the balance between the separately excitedfield 35 andthe field winding 34, the field winding 34 will now predominate, therebycausing the generator 27 to build up practically simultaneously a.voltage corresponding in value and direction to the increase in thecurrent of the circuit of the electrode 10 The armature of the electrodemotor 14 will be simultaneously energized to'operate the electrode 10 toraise the electrode until the value of the current in the electrodecircuit becomes the normal value which it is desired shall bemaintained. I

In case the current in the electrode circuit decreases below thepredetermined normal value, the cathode 20 will be heated to acorrespondinalyr less value, the energization of the field inding 34will be correspondingly decreasedfandthe field winding 35 of thegenerator '27 will nov'i predominate .to reverse the current supplied bythe generator to thereby cause the motor '13 to-,lower the electrode, 10until a stable condition is restored.

It will be apparent from the above that the entire arrangement is verysensitive to changes in the electrical conditions of the arc. supportedby the electrodes. The adjustment of the electrodes is effectedsubstantially coincidentally with the occurrence of the electricalcondition which makes necessary an adjustment of the electrodes. It willalso be observed that the electrode motors are prevented fromoverrunning,

since the motors will operate in each direction to a limit determined bythe value of the voltage induced in the secondary of the corresponding,current transformer:

Furthermore, the motors will operate as regenerative braking generators*returning energy to the supply circuit in case the 6 generated voltageof the motor should at any time be greater. than the voltage of itsrespective generator.

. It will be understood by those skilled in the art that the electricalcondition of the arcsupported byone of the arcing electrodes has aneffect on the electrical condition of themes supported by the otherelectrodes of the furnace, so that the adjustment of one electrode willbe accompanied by the practically simultaneous adjustment ofthe otherelectrodes in case the adjustment of one electrode makes necessarytheadjustment of the'other electrodes to restore the normal conditioninitially determined upon. 0 1 It will be observed that since the energysupplied to the furnace electrodes and the 2 electrodes to energy fordriving the electrode motors is all taken from the source of supply 31,a failure, of said source will not cause the I be lowered .into the;furnace bath.

, In accordance with the provisions of the patent statutes, havedescribed the prin-. .ci lo of operation of my invention, together 0w1th the apparatus which I now consider to represent the best embodimentthereof,

but I desire to have it understood .that the apparatus shown is onlyillustrative: and that the inventionv may be carried out by 5 otherrfieans. r

0 What I claimas new and desireto secure by Letters Patent of the Unitedstatea'isz 1. The combination with. an electrode adapted to support anarc, of means comprislng an electric valve for; regulating the arcingrelation of the said, electrode, and donnections whereby the said valveregulates the arcing relation of said electrdde in accordance with anelectrical condition of the 15 arc supported by. said electrode.

as prism 2. The combination with; an electrode adapted to su port anarc, of an electric valve connecte tobe responsive to an electricalcondition'of the arc supported-by said 1 electrode, andelectro-responsive means controlled by said valve for regulating thearcing relation of the said electrode.

' 3. The combination with an electrode adaptrzyd g an electric valvefor'regulat' the arcing relation of the said electrode, and

connections wherebythe' said valve regulates the arcing relatiom of saidelectrode in #00 supported by the electrode.

accordance wit the current in the are adapted to support an arc, ofmeans comprising an electron discharg device for regulating the ,ar'cingrelation of the said 5 electrode, a current transformer having its tosupport an arc, of means com- 7 4. The combination with an electrodeprimary in the circuit of said electrode and its secondary connected tothe said device, 5

and means controlled by the' said device for regulating the arclngrelation of said electrode. v

5. The combination with an. electrode adapted to support an arc, of anvelectric motor for controlling the arcing relation of said electrode, anelectron discharge device for controlling the said motor, andconnections whereby the said device controls the operation of saidmotonin accordance with the conditions in the circuit in which saidelectrode is included.

' motor for controlling the arcing relation of said electrode, anelectron discharge device and connections whereby said device controlsthe direction and the limit of operation of saidmotor in accordance withconditions in the circuit which the said electrode.

is included. V A

8. .The combination with an electrode adapted to support an arc, of anelectric motor having a/ field and an armature controlling the arclngrelation of said electrode, an electron discharge device, andconnections whereby the said device controls therelative direction ofthe field and armature currents of said motor responsively to acondition of the arcing circuit of said elect-rode. I I

9. The combination with an electrode 6. The combination with anelectrode adapted to support an arc, of-an electric 1 motor forcontrolling the arcing relation of said electrode, a ierator for.supplying current to the sai motor, an electron dis-- charge device andconnections whereby the said device controls the current supplied by Ithe said generator to the said motor in accordance with a condition ofthe arcing cir;

cuit of the said electrode.

10. The combination with an electrbde 3 adapted to support anarc, of anelectric motor for controlling the arcing relation of said electrode, anerator for supplying current to the sai motor, an electron dis---charge device, and connections whereby the said device controls-thevoltage and the di-L rection of current supplied by the said generatorto the said motor in accordance with a condition of the arcing circuitof said electrode.

- 11. The elimination with an electrode 1 adapted to support an are, ofa separately excited motor for controlling the arcing relation of saidelectrode, a separately excited generator for supplying the current tothe armature of said motor, an electron dis charge device andconnections whereby the said device controls the voltage and thedirection" of current supplied by the said generator to the said motorin accordance tions whereby the said electron discharge device controlsthe direction and the limit of operation of the'said motor in accordancewith a condition of the supply of en- "ergyto the said translatingdevice.

13. The combination with an alternating current supply circuit, of anelectric translating device connected to be supplied with current fromthe said supply circuit, a direct current motor for regulating the saiddevice, a h eated cathode electron discharge device, and connectionswhereby the said electron discharge device controlsthe energization ofthe said motor in accordance with the current taken by the saidtranslating device.

14. The combination with an alternating current supply circuit, of anelectric translating device connected to be supplied with current fromthe said supply circuit, a direct current motor for regulating the saiddevice, a direct current generator connected to supply the current forthe said motor, a

heated cathode electron discharge device, and connections whereby thesaid electron discharge device controls the voltage and the direction ofcurrent supplied by the said generator to the said motor in accordancewith the current taken by'the said translating device. x

15. A regulator for an electric arc furnace having a-p1urality ofcooperating elec trodes connected to an' alternating current supplycircuit, comprising a separate direct current motor for regulating thearcing "relation of each electrode, a separate direct current generatorfor supplyingthe current to each of said electric motors, a separateheated cathode electron discharge device for controlling each of saidgenerators, and connections whereby the said devices control theirrespective generators in accordance with the current passing throughtheir re:

spective electrodes. p

In witness whereof, I have hereuntoset my hand this 13th day of October,1921.

EDWARD HORSTKOTTE.

